The present invention relates to a transmitter mounting structure for a tire condition monitoring apparatus, and more specifically, to a transmitter mounting structure for a wireless type tire condition monitoring apparatus enabling tire conditions, such as tire air pressure, to be checked from the passenger compartment of a vehicle.
A transmitter for a tire air pressure monitoring apparatus is mounted on a wheel and located in a tire. A mounting structure of the transmitter includes a valve stem, a spring element, and an electronic module for measuring the air pressure of the tire and transmitting the measured air pressure. The valve stem is coupled to the spring element. The spring element has a clamp plate coupled to the electronic module. The clamp plate clamps the electronic module to the wheel. When the wheel is rotating, various forces, such as centrifugal force, act upon the electronic module. The elastic force of the spring element acts to effectively suppress or control the movement of the electronic module. Accordingly, the electronic module is pressed against a drop center of the wheel when mounted on the wheel (refer to U.S. Pat. No. 5,956,820).
The fastening device described in U.S. Pat. No. 5,956,820, however, cannot cope with all the cross sectional shapes of wheels. That is, there are many types of wheels with different cross sectional shapes, such as, wheels with a drop-center rim, a shallow base rim, a broad flat-base rim, and a broad deep rim. Therefore, the valve stem and the casing which houses the transmitter, and ultimately the mounting angle of the electronic module, is unambiguously determined by the cross sectional shape of the wheel. As a result, in order to mount the electronic module in a state pressed against the drop center of the wheel, the spring element and clamp plate must be in correspondence to the cross sectional shape of the wheel.